U.S. Publication No. 2014/0084817 discloses a method for energy and power management in dynamic systems comprising supercapacitors. Here, the sum of the voltage of a battery and of the supercapacitor is applied to a consumer in a first switching state. In the normal load state, the secondary side of the DC voltage/DC voltage converter is connected to the consumer.
U.S. Publication No. 2012/0261982 discloses an on-board multi-voltage electrical system for a motor vehicle. A plurality of DC voltage/DC voltage converters are used, capacitors being associated with said plurality of DC voltage/DC voltage converters. Different operating states can be achieved by means of toggle switches.
U.S. Publication No. 2014/026559 discloses a high-power on-board electrical system for a motor vehicle. Said high-power on-board electrical system has a high-power electrical bus which is at least partially supplied with power by a converter which obtains its input power from the battery of the vehicle. The high-power electrical bus can be at least partially uncoupled from the motor vehicle battery. Consumers with a high electrical power, such as an active wheel suspension or an active chassis or an active suspension for example, are supplied with power by means of the high-power electrical bus.
A consumer with a high electrical power typically has a maximum power consumption of >1 kW or current consumption of >80 A, an average power consumption of 300 W or current consumption of 25 A.
U.S. Pat. No. 8,971,073 discloses a system and a method for bridging (bypassing) multistage DC voltage/DC voltage converters in networks with batteries. No capacitors are used.
U.S. Pat. No. 5,179,508 discloses a voltage supply system comprising a battery and a DC voltage/DC voltage converter. Said DC voltage/DC voltage converter is always in the power flow, it is not bridged.
However, the inventors herein have recognized issues with the above configurations. If the high-power consumers (e.g., high-load consumers) are operating at very low power demands or at high constant loads, energy conversion losses occur in the DC voltage/DC voltage (e.g., DC/DC) converter(s), which dissipate into heat that is transferred to the ambient. Further, these conversion losses decrease the vehicle's fuel efficiency, or in the case of plug-in vehicles such as electric vehicles or plug-in hybrids, add to the total energy consumed. Accordingly, a system is provided herein to at least partly address the above issues. In one example, the system includes an on-board electrical system for motor vehicles, comprising: a battery; a power source which is provided for charging the battery; conventional automotive electrical consumers; a DC voltage/DC voltage converter which, on its primary side, is connected to the battery and, on its secondary side, is connected to a high-load consumer so as to form an electrical subsystem with an energy storage device; an electronic or mechanical switch that connects the high-load consumer to either the energy storage device that is charged through the secondary side of the DC voltage/DC voltage converter, or through a primary power source (e.g., the battery or power source) via an upper diode, wherein in a first switching position, the high-load consumer is supplied power by the primary power supply via the upper diode and, in a second switching position of the switch, the high-load consumer is connected to the storage device and the output of the DCDC-converter, wherein the upper diode allows the primary power supply to supply the high-load consumer, but blocks a current flow in the opposite direction to force any regenerated current to be stored in the energy storage device, wherein a lower diode is connected between the energy storage device and the high-power load, wherein the lower diode is implemented to always block a current flow from the storage device to the conventional loads powered by the primary power supply but transmits a current flow in the opposite direction to facilitate the recuperation of regenerated power from the high-power load; a controller which controls and operates the switch between the first and the second switching positions; and a device for detecting electrical power of the high-load consumer which is associated with the high-load consumer and is connected at the output end to the controller.
In this way, a DC voltage/DC voltage converter may be bridged when the power requirement of a high-power consumer is low (for example less than 40% to 60% of the rated power of the DC voltage/DC voltage converter) and/or constant (for example fluctuation in the current value of less than 10% of the rated value of the power of the high-power consumer). However, the high-power consumer may be supplied with power via the converter when the power requirement of the high-power consumer is high or changes rapidly (for example fluctuation in the current value of greater than 10% of the rated value of the power of the high-power consumer within one second). In one example, a rated power may be defined as the highest power (e.g., maximum) input allowed to flow through a consumer.
Owing to the configuration of the disclosure, the energy efficiency of the system is increased when the DC voltage/DC voltage converter is bridged. Converters of small size may then be used, for example a converter for 210 W may be used instead of a converter with a 300 W rated power. Continuous loading and continuous incidence of heat loss in the converter do not take place. The converter may be used only in relatively short phases of high-power requirement and heat loss arises only in said phases. This is advantageous; energy, in particular fuel, is saved.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.